Fixed hybrid dental attachment assembly and methods of use

ABSTRACT

A frictionally-retained detachable dental attachment assembly or anchor device is designed to attach a dental appliance with a tooth root or implant. The assembly includes a denture attachment housing for securing in the dental appliance, an abutment attached with a tooth root or implant, and a compressible retention member with a first end in fixed attachment with the cap and a second end in snap engagement with the abutment via a frictionally-retained ball secured within a cavity of the abutment. The retention member is formed using a compressible material to allow the ball to compress and the retention member to flex while inserting the ball into the cavity. Additional friction-retained and fixed attachment configurations of the dental anchor device are provided, along with methods of securing a dental appliance in a subject&#39;s mouth by means of the friction-retained and fixed attachment dental anchor devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/009,713 filed on Jan. 28, 2016, which is a continuation-in-part ofU.S. patent application Ser. No. 14/806,616 filed on Jul. 22, 2015,which claims the benefit of Provisional Application Ser. Nos. 62/028,314filed on Jul. 23, 2014 and 62/027,780 filed on Jul. 22, 2014, and thecontents of each of the aforementioned applications are incorporatedherein by reference in their entirety.

BACKGROUND Field of the Invention

Devices and methods provided herein relate to a dental attachmentassembly for anchoring a dental appliance with a base structure such asa tooth root or dental implant.

Related Art

Dental anchoring or attachment assemblies are utilized to anchor adental appliance with a dental implant or tooth root, typically byfitting two or more partially-movable components together to provide animproved fit and comfort. In some assemblies, male and female parts havemating, snap engageable formations for releasably securing the male partto the female part. For example, the female part has a socket and themale part has a head for snap engagement in the socket. However, asrepeated impacts of the socket and head may damage the retentive head ofthe male and cause wearing due to friction of the components as theymove, a compressible annular ring may be provided to absorb thefrictional forces and act as a cushion between the socket and the head.However, even the ring may wear out over a period of time and need to bereplaced, requiring regular maintenance of the dental anchoring assemblythat is uncomfortable and inconvenient for the patient. Furthermore, toallow the compressible annular ring to be easily removed and replaced,the ring may be provided with a securing mechanism on a mating surfacewith the socket (such as a threaded portion), which further adds to thecost and complexity of the dental anchor assembly.

It is therefore desirable to avoid the need for continued maintenanceand simplify the design of the dental anchoring assembly.

SUMMARY

Embodiments described herein provide for a frictionally-retaineddetachable dental attachment assembly for adjustably attaching a dentalappliance with a tooth root or implant. The dental attachment assemblyincludes a cap or denture attachment housing for securing in the dentalappliance, an abutment for attachment to a tooth root or implant, and aretention member with a first end in fixed attachment with the cap and asecond end in snap engagement with the abutment via africtionally-retained ball or head of the retention member securedwithin a cavity of the abutment. The retention member is formed using acompressible material to allow the ball to compress and the retentionmember to flex while inserting the ball into the cavity. Additionalfriction-retained and fixed attachment configurations of the dentalanchor device or attachment assembly are provided, along with methods ofsecuring a dental appliance in a subject's mouth by means of thefriction-retained and fixed attachment components of the attachmentassembly.

In one aspect of the invention, a dental attachment assembly comprises adenture attachment housing for securing to a dental appliance, thehousing having an open end defining an inner cavity; an abutment havingan upper opening with a socket; and a retention member configured with athreaded portion to securely attach with the housing at a first end andconfigured with a compressible head or ball at a second end tofrictionally engage with the socket of the abutment at a second end toform a frictional fit between the head and the socket and securelyretain the dental appliance and abutment. In one embodiment, the sockethas an annular inward projection or barb having an undercut, theprojection having an inner diameter smaller than the outer diameter ofthe compressible spherical head, whereby the projection compresses andbites into an opposing portion of the spherical head to retain the headin the cavity, and the undercut resists removal of the head from thecavity.

Other features and advantages of the present invention will become morereadily apparent to those of ordinary skill in the art after reviewingthe following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and operation of the present invention will be understoodfrom a review of the following detailed description and the accompanyingdrawings in which like reference numerals refer to like parts and inwhich:

FIG. 1 is a vertical cross-sectional view of a first embodiment of adental attachment assembly having a denture attachment housing, anabutment, and a retention member, with the parts shown in a fullyassembled condition in which the denture attachment housing is securedto the abutment via the retention member;

FIG. 2 is a perspective view of one embodiment of the retention memberof FIG. 1;

FIG. 3 is a side elevation view of the retention member of FIG. 2;

FIG. 4 is a vertical cross-sectional view of the dental attachmentassembly of FIG. 1 in an angled, unattached configuration duringassembly of the parts;

FIG. 5 is a vertical cross-sectional view of the dental attachmentassembly of FIGS. 1 and 4 in an attached, angled configuration ascompared to the aligned configuration of FIG. 1;

FIGS. 6A, 6B and 6C are cross-section views illustrating steps of aprocess of attaching the retention member with the abutment in theassembly of FIGS. 1 to 5, illustrating a compression of a ball and shaftportion of the retention member, according to an embodiment of theinvention;

FIG. 7 is a vertical cross-sectional view illustrating a secondembodiment of a dental attachment assembly;

FIG. 8 is an exploded side elevation view illustrating a thirdembodiment of a dental attachment assembly which has an outer surfaceretention configuration;

FIG. 9 is an exploded cross-sectional view of the assembly of FIG. 8;

FIG. 10 is a bottom side perspective view illustration of the retentionmember of the assembly of FIGS. 8 and 9;

FIG. 11 is a top side perspective view illustration of the retentionmember of FIG. 10;

FIG. 12 is a side view illustration of the retention member of FIGS. 10and 11;

FIG. 13 is a cross-sectional view of the retention member on the lines13-13 of FIG. 12;

FIG. 14 is a side view illustration of an embodiment the retentionmember with an acrylic finishing line;

FIG. 15 is a cross-sectional view of the retention member along lines15-15 of FIG. 14;

FIG. 16 is a side elevation view of an acrylic pick up cap embodiment ofthe denture cap;

FIG. 17 is a cross-sectional view of the acrylic pick up cap along lines17-17 of FIG. 16;

FIG. 18 is a side elevation view of a burn out cap embodiment of thedenture cap, according to an embodiment of the invention;

FIG. 19 is a cross-sectional view of the burn out cap along lines 19-19of FIG. 18;

FIG. 20 is an enlarged side elevation view of the abutment of theassembly of FIG. 8;

FIG. 21 is a cross-sectional view of the abutment on the lines 21-21 ofFIG. 20;

FIG. 22 is a side elevation view illustrating an embodiment of ascrew-retained dental attachment assembly;

FIG. 23 is a cross-sectional view on the lines 23-23 of FIG. 22;

FIG. 24 is a side elevation view of the assembly of FIGS. 22 and 23 withan added acrylic pick up cap;

FIG. 25 is a cross-sectional view on the lines 25-25 of FIG. 24;

FIG. 26 is a side elevation view of the assembly of FIGS. 24 and 25 inan angled configuration;

FIG. 27 is a cross-sectional view on the lines 27-27 of FIG. 26;

FIG. 28 is a side elevation view of the outer surface retentionconfiguration of FIG. 8 in an angled orientation;

FIG. 29 is a cross-sectional view on the lines 29-29 of FIG. 28;

FIG. 30 is a flow diagram of one embodiment of a method of attaching adental appliance with at least one dental attachment assembly;

FIG. 31 is an exploded cross-sectional view of another embodiment of adental attachment assembly;

FIG. 32 is a cut-away view of the assembly of FIG. 31 in a fullyassembled condition;

FIG. 33 is an enlargement of part of the assembly in FIG. 32illustrating the engagement between a barb or projection in the socketand the ball or head of the retention member;

FIG. 34 is an enlarged side perspective view of the denture attachmenthousing of FIG. 33, illustrating an anti-rotation flat in the outersurface;

FIGS. 35A to 35C are side elevation views of a plurality of retentionmembers with balls or heads of varying materials or configuration forproviding different amounts of retention force;

FIG. 36 is an enlarged side perspective view of one embodiment of aprocessing cap for forming a processing cap cavity in a dental appliancesuitable for bonding to the denture attachment housing of FIGS. 31 to33;

FIG. 37 is a cross-sectional view of the processing cap of FIG. 36;

FIG. 38 is a cut-away view similar to FIG. 32 illustrating the dentureattachment assembly of FIGS. 31 to 34 with the processing cap of FIGS.36 and 37 engaged over the denture attachment housing;

FIG. 39 is a perspective view illustrating one embodiment of an abutmentanalog for use during model fabrication;

FIG. 40 is a vertical cross-section view of the abutment analog of FIG.39;

FIG. 41 is a cut-away view similar to FIG. 38 illustrating the abutmentanalog of FIGS. 39 and 40 replacing the abutment in the dentureattachment assembly of FIGS. 31 to 34 and with the processing cap ofFIGS. 36 and 37 mounted on the denture attachment housing;

FIG. 42 is a vertical cross-sectional view of one embodiment of a waxingcap for creating a cavity in a cast framework in a wax-up procedure;

FIG. 43 is a side perspective view of the dental attachment assembly ofFIGS. 31 to 34 with the waxing cap of FIG. 42 engaged over the dentureattachment housing;

FIG. 44 is a cross-sectional view of the assembly and waxing cap on thelines 44-44 of FIG. 43;

FIG. 45 is a top side perspective view of a snap-on healing cap forcovering up the opening in the abutment of FIGS. 31 to 33 during thehealing phase;

FIG. 46 is a bottom perspective view of the healing cap of FIG. 45,illustrating the retention head analog;

FIG. 47 is partially sectioned front elevation view of the healing capof FIGS. 45 and 46 secured to the abutment of FIGS. 31 to 33; and

FIGS. 48 and 49 are flow diagrams illustrating methods of attaching adental appliance with at least one dental attachment assembly in the labor in a patient's mouth, respectively.

DETAILED DESCRIPTION

Certain embodiments disclosed herein provide for a frictionally-retaineddetachable dental anchor device or dental attachment assembly forattaching a dental appliance with a tooth root or implant. The dentalattachment assembly includes a cap or denture attachment housing securedin the dental appliance, an abutment attached with a tooth root orimplant, and a compressible retention member with a first end in fixedattachment with the cap and a second end in snap engagement with theabutment via a frictionally-retained ball secured within a cavity of theabutment. The retention member is formed using a compressible materialto allow the ball to compress and the retention member to flex whileinserting the ball into the cavity. Additional friction-retained andfixed attachment configurations of the dental anchor device areprovided, along with methods of securing a dental appliance in asubject's mouth by means of the friction-retained and fixed attachmentdental anchor devices.

After reading this description it will become apparent to one skilled inthe art how to implement the invention in various alternativeembodiments and alternative applications. However, although variousembodiments of the present invention will be described herein, it isunderstood that these embodiments are presented by way of example only,and not limitation. As such, this detailed description of variousalternative embodiments should not be construed to limit the scope orbreadth of the present invention as set forth in the appended claims.

The dental attachment assembly described herein functions similar to afixed dental attachment system, yet can be more easily removed by adental professional using a special tool. The dental attachment assemblydescribed herein is useful to attach a dental appliance, such as adenture, with an implant and provide a retentive force of about 10 to 75pounds, while also providing ease of engagement of the retention memberwith the abutment due to the compressible nature of the materials usedand the friction-retained snap-fit of the ball and socket components.

As will be described in detail below, the retention member is formedfrom a compressible material—such as a polymer or soft metal—to allowthe retention member to compress and flex while being attached ordetached from an abutment secured to the implant. The compressible andflexible retention member can then be secured with the abutment at avariety of angles, which is often necessary when securing a dentalappliance to a plurality of implants extending at different anglesacross a person's upper or lower mandible. Additionally, thecompressible ball eliminates the need for a separate compressibleannular ring to be positioned in the socket of the abutment between theretention member and interior abutment walls, as well as the need for asecuring mechanism for securing the annular ring to the abutment walls.The dental attachment assembly is therefore easier to manufacture andrequires less maintenance once inserted.

A. Dental Attachment Assembly

FIG. 1 illustrates one embodiment of a dental anchoring or attachmentassembly 100 which may be attached with an implant (not shown) that maybe anchored to a bone or other base structure (not shown) such as atooth root. The assembly includes an abutment 102 which is secured tothe implant and a cap or denture attachment housing (DAH) 104 which issecured in a recess of a dental appliance. A retention member 106 servesto provide the frictionally-retained connection between the cap and theabutment. To this end, the retention member includes a shaft 108 whichhas a threaded end portion 110 in a threaded connection with acorresponding threaded bore 111 in the cap. A second end of the shaftwhich interfaces with the abutment includes a head 112 which issubstantially spherical in shape and which is configured to create africtional fit with an inward projection or barb 120 in a socket 114found in an upper opening 116 of the abutment. The head includes acurved surface 118 configured to frictionally engage an annular inwardprojection 120 in the socket, and a flat lower end face 119 with aninwardly directed hexagonal or polygonal shaped recess 121 forengagement with a suitable tool when the retention member is threadablyengaged in bore 111 of cap 104. The inward projection has an undercut123 that is engaged with the head 112. The socket does not necessarilyneed to be curved to match the curved surface 118 of the head 112.Instead, the head 112 is in contact with the socket only at projection120 in most or all attachment orientations. In the embodiment in FIG. 1,the outer surface of the head 112 is convex, while the outer end face119 of the head is flat in order to provide for a closer fit of the head112 with the abutment. The inward projection 120 is configured to have afriction fit with the corresponding diameter of the head 112 at themouth of the socket 114.

One benefit of the compressible material for the retention member 106 isthat the diameter of the head 112 may be altered to increase or decreasethe retentive force provided by the frictional-fit or compression of thehead 112 engaging with undercut barb 123 of annular projection 120. Thegreater the maximum diameter of head 112, the higher the retentiveforce, since the inward projection cuts further into the head when fullyengaged. A smaller diameter head 112 provides less retentive force.Retention force may also be varied by using different, softer or hardercompressible materials for head 112, as described in more detail belowin connection with the modified embodiment of FIGS. 31 to 35C. FIGS. 2and 3 illustrate the external surface of the head 112 of one embodimentof retention member 106. The outer ball-shaped or convex curved surface118 may have a series of flats or flattened portions 119 around thecircumference of surface 118 to reduce the amount of friction betweenthe curved surface 118 of the head and the corresponding curved surfaceor projection 120 of the socket. In an alternative embodiment, no flatsare provided and the head has a smooth outer convex surface. A smoothconvex surface increases the amount of friction between head 112 andprojection 120, since the projection digs more deeply into thecompressible surface of the head in the attached configuration ofFIG. 1. Thus, one, two, or all of the following parameters may be usedto vary the retention force of the head in the abutment socket: headdiameter, head shape, and the selected compressible material of thehead. The retention force may vary from anywhere between about 10 toabout 75 pounds, although some embodiments may provide as little asabout 1 pound of retention force for use in the initial positioning ofthe dental appliance and dental anchoring device.

The cap 104 is configured with an annular internal surface 122 which maybe curved to engage with a corresponding curved outer surface 124 of theabutment, providing an additional frictional fit for the dentalattachment assembly.

In one embodiment, a ball flange 126 is provided on shaft 108 at apredetermined spacing below threaded portion 110. Flange 126 extendsperpendicular to the axial direction of the shaft 108 and acts as a stopby engaging an opposing surface 127 of the cavity in cap 104 whenthreaded stem 110 is threaded into bore 111. The ball flange 126 servesto help locate the ball 112 within the socket 114 and cap 104 andprevent vertical movement of the assembly.

In the embodiment described herein, the retention member may be formedfrom a compressible or elastomeric material such as a polymer or a softmetal, non-limiting examples of which include polymers such as polyetherether ketone (PEEK), polyoxymethylene or acetal polymers such asDelrin®, and soft metals such as nickel titanium (nitinol), pink TiCN(titanium carbo nitride) or titanium. The soft metal may be a coating onthe surface of the head portion in some embodiments. In one embodiment,the surfaces may be coated with a gold nitride coating to reducefriction.

FIG. 4 illustrates the dental attachment assembly in an angled,unattached configuration prior to full insertion of head 118 in socket116, 114, illustrating the varying angles at which the retention member106 may be snap-fit into the abutment. In practical applications, theimplant may protrude from the bone or tooth root at varying angles fromthe ideal vertical angle due to the structure of the bone or theplacement of the implant during surgery. The dental anchoring orattachment assembly therefore corrects any angular displacement byrotation of the head 112 in the socket 114. In one embodiment, the angleof approach of the head with respect to the abutment may vary up toabout 20 degrees in any direction from the vertically-alignedorientation shown in FIG. 1. In combination with another implant alsooffset at a similar angle, the dental anchoring device may thereforeprovide as much as about 40 degrees of angle correction.

FIG. 5 illustrates of the dental attachment assembly in the angledorientation shown in FIG. 4 but where the retention member 106 is nowsnap-fit into the socket 114 of the abutment 102. As illustrated in FIG.5, the head 112 may be secured within the socket 114 despite thedifferential angle. Furthermore, the annular surface 122 of the cap 104is also still frictionally engaged around the outer curved surface 124of the abutment with the offset indicated in FIG. 5, and the annularprojection 120 is frictionally engaged at an angle around the opposingannular surface portion of head 118.

FIGS. 6A-6C are side cutout view illustrations of the flexing andcompression of the head 112 and shaft 108 of the retention member 106during a process of attaching the retention member with the abutment atthe angle already illustrated in FIGS. 4 and 5, according to anembodiment of the invention. As noted above, the retention member 106 ismade of a compressible polymer or soft metal material which is alsocapable of flexing in the case of engagement with an offset abutment. Asillustrated specifically in FIG. 6B, the shaft 108 and head 112 of theretention member 106 are flexing and compressed due to the angle of theabutment with respect to the retention member 106. However, as shown inFIG. 6C, once the retention member 106 is frictionally snap-fit into thesocket 114, the flexure and compression is reduced such that theretention member 106 and abutment 102 provide a secure fit withoutinducing an undue amount of stress on the retention member. At the sametime, annular projection or barb 120 compresses or bites into opposingregions of the curved surface 118 of head 112, securing cap 104 toabutment 102.

B. Screw-Retained Configuration

FIG. 7 illustrates a modified, screw-retained dental attachmentassembly, according to another embodiment of the invention, whereinstead of the ball and socket configuration, a cantilevered screw 128protrudes through the cavity 116 in the abutment 102 and forms athreaded connection 130 with a corresponding threaded bore in theabutment 102 to create a fixed connection. As illustrated above withregard to FIG. 1, the annular surface 122 of the cap 104 provides asliding retentive surface with the outer curved surface 124 of theabutment to allow for minimal rotation of the screw 128 and cap 104 withrespect to the abutment.

This embodiment is useful for obtaining a highly secure fit between animplant and the dental appliance which will provide a significantretentive force. As described further below, this configuration may onlybe needed for one implant where several implants are being used tosecure a dental appliance across the surface of a person's mouth.

C. Outer Surface Retention Configuration

In another alternative embodiment illustrated in FIGS. 8 and 9, anabutment 132 is utilized with a cap-like retention member 134 and adenture cap 136 to provide retentive force on the outer surface of theabutment without the use of the head and socket configuration. FIGS. 8and 9 are exploded side elevation and cross-sectional illustrations,respectively, of the denture cap 136, retention member 134 and abutment132 of an outer surface retention configuration of a dental attachmentassembly, according to an embodiment of the invention. As illustratedherein and also above in FIG. 1, the outer surface 124 of the abutment130 forms a curved surface which mates with a corresponding curvedsurface 122 of the retention cap 132 to form a frictional fit. Theretention member 134 has a threaded portion 138 configured for threadedengagement in corresponding threaded bore 140 in denture cap 136. Inthis embodiment, bore 140 is not a through bore through the cap butinstead terminates in the cap, and has a closed top or end wall 141. Thethreaded bores in the denture caps of any of the preceding embodimentsmay also have similar closed end walls in alternative embodiments.

FIGS. 10 to 13 are illustrations of the retention cap or member 134 ofthe outer surface retention assembly of FIGS. 8 and 9, according to anembodiment of the invention, showing the threaded surface 138. FIGS. 10and 11 are perspective views taken from opposite ends of retention cap134, while FIGS. 12 and 13 are side elevation and cross sectional views,respectively. FIGS. 14 and 15 illustrate retention cap 124 with anacrylic finishing line 142 where acrylic from the surrounding denturecan create a smooth finish with the denture cap, according to anembodiment. FIG. 15 illustrates inner spherical retention surface 122 ofthe retention member 134 which has an outer vertical surface 144 whichserves as a wraparound retentive feature.

FIGS. 16 and 17 are side elevation and cross-sectional views,respectively, of an acrylic pick up cap 146 embodiment of the denturecap 136, according to an embodiment of the invention; and FIGS. 18 and19 are side elevation and cross-sectional illustrations, respectively,of a burn out cap 148, according to an embodiment of the invention. Theacrylic pick up cap 146 includes a plurality of retaining channels 150that acrylic will flow through to hold a dental appliance such as adenture with the cap 146. The burn out cap 148 is used in cast barsituations.

FIGS. 20 and 21 are side elevation and cross-sectional views,respectively, of the abutment 132 of the outer surface retentionconfiguration of FIGS. 8 and 9, according to an embodiment of theinvention. The abutment has an internal thread 152 for securing threadedcomponents such as a healing collar, impression coping screw andCantilever screw during processing. Additionally, an internal drivingfeature 154 is visible, which serves to tighten the abutment into theimplant.

FIGS. 22 and 23 are side elevation and cross-sectional views,respectively, of a screw-retained embodiment of the outer surfaceretention configuration, according to an embodiment of the invention,where a cantilever screw 128 as illustrated in FIG. 7 is secured throughan opening 129 of the retention cap 134 and into a threaded connectionwith the abutment 132. Screw 128 has a threaded end portion 137 whichengages the internal thread 152 of abutment 132. FIGS. 24 and 25 areside elevation and cross-sectional views, respectively, of acrylic pickup cap 146 of FIGS. 16 and 17 in use with the retention cap 134 andabutment 132 of screw-retained embodiment of FIGS. 22 and 23, accordingto an embodiment. Pick up cap 146 is threaded onto the other threadedportion 138 of retention cap or member 134, and screw 128 is engagedthrough the open end of pick up cap 146 and through bore 129 ofretention member 134 to engage the threaded bore 152 in abutment 132.

As illustrated, FIGS. 26 and 27 are side elevation and cross-sectionalviews, respectively, of the outer surface retention configuration in anangled orientation, according to an embodiment, with a modified acrylicpick up cap 147 similar to cap 146 of FIGS. 24 and 25 but having aclosed upper end. FIGS. 28 and 29 are similar side elevation andcross-sectional views, respectively, of the outer surface retentionconfiguration excluding the acrylic pick up cap 147.

D. Method of Use

FIG. 30 illustrates one embodiment of a method of attaching a dentalappliance to a plurality of implants using the various dental attachmentassemblies described above. For example, where a patient is being fittedwith a complete upper or lower denture, a plurality of implants will beinserted into the bone structure across the area where the denture is tobe placed. In some embodiments, as few as 2 or as many as 6 implants maybe used. In the embodiments described herein, the frictionally-retaineddental attachment assembly may be utilized for the majority of theimplants while fewer of the implants—even just one—utilize the fixed, orscrew-retained, dental attachment assembly. This provides flexibility inattaching the majority of the implants with the dental appliance whilestill providing a fixed connection at one implant which will ensure theretention of the entire dental appliance against any amount of retentiveforce.

In a first step 1302, an abutment is secured to an implant or other rootstructure that will support the dental appliance. Next, thefrictionally-retained retention members are fitted onto at least oneabutment (step 1304), and at least one fixed retention member isattached to at least one abutment (step 1306). In step 1308, thefriction-retained retention members are attached to their respectivecaps, and in step 1310, the fixed retention members are attached totheir respective caps. In step 1312 the non-swiveling retention memberis removed from the cap and a swiveling retention member is insertedinto the cap. In step 1312, the dental appliance may be engaged onto theabutment by the snap engagement of the retention member onto theabutment and may be swiveled or rotated into place through use of theswivel joint between the cap and retention member, which is furtherenhanced by the concave recess within the cap.

E. Modified Dental Attachment Assembly

FIGS. 31 to 34 illustrate another embodiment of a dental attachmentassembly 160 which has a similar retention member to the embodiment ofFIGS. 1 to 6C but has a modified abutment 162 for attachment to a toothroot or dental implant, and a modified cap or denture attachment housing(DAH) 164 for securing in a dental appliance. Retention member 165secures denture attachment housing 164 to abutment 162, as illustratedin FIG. 32. A plurality of retention members of different materials orball shapes or dimensions may be provided for providing a range ofdifferent retention forces based on the installation force requirement,as described in more detail below in connection with FIGS. 35A to 35C.

Abutment 162 has a head portion 166 with a rounded or convex outersurface 167, a socket 168 extending inwardly into head portion 166, anda shaft 170 extending away from head portion 166 for engagement in acorresponding mating bore in a tooth root or implant. Shaft 170 has aseries of cylindrical portions of stepped diameter extending from flange171 at the lower end of head portion 166, and an externally threaded endportion 172. Abutment 102 of the first embodiment had an internal hexdrive 114 below the projection or barb 120, at the inner end of thesocket. Abutment 162 of this embodiment instead has a hex drive portion173 close to a tapered entrance opening 174 at the outer end of socket168, which is easier to access with a removal or insertion tool than theinternal hex of the first embodiment. Additionally, the screw threadedbore extending from the socket into the shaft as seen in FIG. 1 to allowscrew retention is removed. This eliminates a food trap which isdifficult to clean, and also reduces fabrication complexity. Eliminationof this threaded bore also increases strength of the abutment andincreases the amount of clearance provided for the head or ball portionof the retention member. In one embodiment, the hex drive portion 121 ofthe first embodiment was a 0.050 inch hex drive. In one embodiment ofabutment 162, hex drive portion 173 at the entrance opening is a 0.100inch hex drive. Removing the internal threads and internal hex at theinner end of the abutment socket allows some abutments to be shorter inlength due to thicker walls.

A step 176 is provided at the lower end of hex drive portion 173, and isfollowed by a reduced diameter portion 177 of the socket. An annular,inwardly directed projection or barb formation 178 is located at the topof socket portion 177. Annular projection 178 is similar in function toprojection 120 of the first embodiment, but is of different shape, asseen in FIGS. 31 to 33. Projection 178 has a rounded convex portion withan undercut 180 which forms a sharp edge or barb which tends to dig intoan opposing surface of the head portion of retention member 165 toresist removal of the retention member from the socket, as described inmore detail below and illustrated in the enlarged view of FIG. 33.

Denture cap or attachment housing 164 has an end wall 182 and an annularskirt 184 extending from end wall 182. Housing 164 has a generallytapered outer surface 185, as best seen in FIGS. 32 and 34. The innersurface of skirt 184 defines a cavity 186 having concave inner surfaceportion 187 configured for engagement with the convex outer surface 167of abutment 162 in the mated condition of the parts (see FIG. 32). Inthis embodiment, a threaded bore 188 extends inwards from the inner endof cavity 186 and terminates in end wall 182, unlike the embodiment ofFIGS. 1 to 6C where the threaded bore 111 extends through the cap endwall and is open at both ends. The cavity 183 has an annular indent 189between concave surface portion 187 and threaded bore 188 which definesstop surface 190 having a similar function to stop surface 127 ofFIG. 1. Outer surface 185 has an outer groove 192 adjacent the outer orupper end face, which provides a mechanical feature or indent foradhesive, and an annular rim 193 at its inner or lower end. Ananti-rotation flat 194 is provided on the outer tapered surface of thehousing (see FIG. 34).

Retention member 165 has a flexible shaft or neck 195 and a generallypart-spherical or convex head or ball 196 at the end of neck 195 forsnap engagement in the socket of abutment 162, as described in moredetail below. Lead-in end 197 of the spherical surface engages taperedentrance opening 174 of the abutment socket to help guide the head intothe socket. Shaft or neck 195 has a threaded end portion 199 configuredfor threaded engagement in threaded bore 188 of cap 164, and an annularflange 200. The closed outer end of the threaded bore in this embodimentprevents adhesive from entering the bore and bonding to the retentionmember during assembly. As in the first embodiment, head 196 has a flatouter end face 191 with a hex indent 198 for engagement with aninsertion tool for tightening threaded shaft portion 199 into matchingthreaded bore 188 of cap 164 until annular flange 200 engages stop face190 at the inner end of annular portion 189 of cavity 186. The portionof the neck or shaft 195 between annular flange 200 and head 196 is thinenough to deflect to accommodate engagement of the head portion in anoffset abutment, in the same manner as described above in connectionwith FIGS. 6A to 6C illustrating the offset attachment of the retentionmember in the abutment of the first embodiment. In one embodiment, thematerial used in manufacture of the retention member and the neckdimensions are selected to permit insertion of the head portion inabutments with offsets of up to twenty degrees or up to thirty degreeswith low or minimal risk of breaking.

In one embodiment, retention member 165 is formed from a compressible orelastomeric material as in the previous embodiments, such as a polymeror a soft metal, non-limiting examples of which include polymers such aspolyether ether ketone (PEEK) or polyoxymethylene or acetal polymerssuch as Delrin®, and soft metals such as nickel titanium (nitinol), pinkTiCN (titanium carbo nitride) or titanium. The soft metal may be acoating on the surface of the head portion in some embodiments. In oneembodiment, the surfaces may be coated with a gold nitride coating toreduce friction.

The frictional snap-fit engagement of the ball or head 196 in the socketof retention member 165 is similar to that described above in connectionwith the first embodiment. FIG. 32 illustrates the head 196 fullyengaged in socket in the case of an aligned abutment. The maximum convexdiameter of head 196 is slightly greater than that of the inwardprojection 178, so that the compressible material of the head iscompressed slightly as the head 196 is forced into the socket. Once thehead is frictionally snap-fit into the socket in the positionillustrated in FIG. 32, the sharp edge or barb 180 bites into the ballto resist removal, similar to an arrow head, as best seen in theenlarged view of FIG. 33. This annular detent or sharpened feature inthe abutment grabs the ball or head 196 for a 360 degree engagement ofthe ball regardless of the angle of insertion. Because retention member165 is made of a compressible polymer or soft metal material, neck orshaft 195 is also capable of flexing in the case of engagement with anoffset abutment, as described above. The barb feature or sharpened edgeconcentrates the compressive load on a smaller area of the ball or headportion, created adding compression and friction and thus increasingretention force. This engagement results in material being sheared awayfrom head 196 during prosthesis removal by a dental professional,requiring the retention members of removed prostheses to be replaced.This increases retention consistency. The barb produces little or noincrease in the required insertion force, but increases the retentionforce opposing removal from the abutment.

As illustrated in FIG. 32, there is a significant clearance between head196 of the retention member and socket 168 of abutment in the attachedcondition, and the head portion contacts the socket only at annularprojection or barb 178, 180, as seen in FIG. 33. The socket providesincreased clearance for offset attachment as compared to the firstembodiment where the end of the head 112 is close to the threadedportion of the abutment when attached as illustrated in FIG. 5.

In one embodiment, a set of retention members which have differentamounts of retention force may be provided, and the different membersmay be color coded for ease of initial selection of a retention memberwith a desired retention force at each anchor position of a prosthesis,as well as ease of replacement when needed. When replacing a retentionmember, original function may be maintained by replacing each removedretention member with a corresponding retention member of the samecolor. A clinician may use a mix of retention forces at differentlocations in an appliance due to specific conditions, for example foropposing cantilever forces. Retention forces may be varied in differentways, such as providing retention members of different diameters and/ormaterials, and by providing flats of different sizes. The greater thediameter, the higher the retentive force, since the inward projectioncuts further into the head when fully engaged. A smaller diameter headprovides less retentive force. Retention force may also be varied byusing different, softer or harder compressible materials for head. Theretention force may vary from anywhere between about 10 to about 75pounds, although some embodiments may provide as little as about 1 poundof retention force for use in the initial positioning of the dentalappliance and dental anchoring assembly.

FIGS. 35A-35C illustrate examples of color coded retention membersproviding different retention forces. In one embodiment, a set of fourcolor coded retention members may be provided as follows:

-   1. High retention force—Retention member 165A of FIG. 35A-   2. Medium retention force—Retention member 165B of FIG. 35B-   3. Low retention force—Retention member 165C of FIG. 35C-   4. Lowest retention force—Processing member or ball which is    identical in shape and dimensions to retention member 165C but is of    a more compliant material.    These retention members may be color coded according to any selected    color scheme, for example in one embodiment, retention member 165A    may be green, retention member 165B may be tan, retention member    165C may be blue, and the processing member may be black to    correspond to the color of a commonly used Locator Processing    Insert. The desired color may be provided by a suitable surface    coating or by color of the material used for making the retention    member. Color coding of the retention member helps to ensure    replacement retention members keep the original function by    providing the same or substantially the same retention force as the    replaced retention or ball member. A dental appliance may have    different retention members secured in the denture attachment    housings or caps, depending on the varying amounts of retention or    removal force required at different locations. Thus, with this    assembly, there will be retention members of different colors, which    can each be replaced with a retention member of the appropriate    color when needed.

Removal force may be controlled by ball diameter, flats, and thesoftness of the material. The set of retention members of FIGS. 35A to35C are identical apart from their different colors and the outersurface of the part-spherical head which is modified to provide varyingretention or removal forces, and like reference numbers are used forlike parts as appropriate. All of the retention members 165A, 165B and165C in this embodiment are made of the same material, and in one aspectthey are made from a polymer material such as polyether ether ketone(PEEK), while the processing ball or retention member (not illustrated)is made of a softer material such as an acetone polymer, e.g. Delrin®,and is of shape and dimensions matching retention member 165C of FIG.35C. The outer convex or part spherical surface of the head 196A ofmember 165A of FIG. 35A is completely smooth, while the externalball-shaped or convex curved surfaces of the heads 196B and 196C ofretention members 165B and 165C of FIGS. 35B and 35C, respectively, havea series of flats or flattened portions 119B and 119C around thecircumference of surface to reduce the amount of friction between thecurved surface of the head and the corresponding projection 120 of thesocket, as described above in connection with FIGS. 2 and 3. Flats 119Care larger and slightly deeper than flats 119B, so that the retention orremoval force of ball or retention member 165B is higher than that ofthe retention member 165C. Since no flats are provided on head 196 ofFIG. 35A and the head has a smooth outer convex surface, the amount offriction between head 196 and projection 178 is higher, and theprojection digs more deeply into the compressible surface of the headthan in the retention members of FIGS. 35B and 35C which havesubstantially the same maximum diameter as head 196A apart from theflats. Heads of different dimensions and materials may be provided forvarying frictional forces.

The insertion technique is similar or identical to that described abovein connection with the first embodiment. The neck or stem diameter isdesigned to allow the retention member to be inserted into a divergentimplant with minimal risk of breaking. In one embodiment, the stemallows insertion at up to a thirty degree angle (as described above inconnection with FIGS. 6A to 6C). The shape of the head or ball of theretention member along with the lead-in end 197 of the part-sphericalsurface allows for typical implant divergence.

FIGS. 36 and 37 illustrate an embodiment of a processing cap 210 for usewith the denture attachment assembly of FIGS. 31 to 35C. This part isdesigned to be fabricated or formed into an all acrylic prosthesis, andprovides the position and depth of a pocket into which the dentalattachment housing is subsequently bonded. FIG. 38 illustrates cap 210with the denture attachment housing 164 on an abutment 162. Cap 210 hasan end wall 212 and a tapered annular wall or skirt 214 extending fromend wall 212. The taper of wall 214 matches that of wall 185 of dentureattachment housing (DAH) 164 and provides a lead-in for more preciseguided bonding to the DAH. Wall 214 has inner grooves 215 for adhesiveto improve bonding of DAH 164 into the cap and outer grooves 216 whichprovide indents or features for receiving acrylic. A series of flats 218around the lower end of outer surface 214 provide some degree ofresistance to rotation forces experienced during installation ofretention members 165 or processing members. In one embodiment, both thedenture attachment housing and processing cap are anodized pink.

FIGS. 39 and 40 illustrate one embodiment of an abutment analog 220 foruse during model fabrication, while FIG. 41 illustrates dentalattachment housing 164 and processing cap 210 secured to abutment analog220 with retention ball or member 165. As illustrated in FIGS. 39 and40, abutment analog 220 has a head portion 221 and a downwardlydepending shaft 222, and an inlet opening 223 in the upper end of headportion 221 leading into socket 224. The head portion has a generallycylindrical outer surface with a step in diameter forming a shoulder 225below the upper end of analog 220. As seen in FIG. 41, shoulder 225engages the lower end of DAH 164 on attachment to the analog to restrictor prevent tipping or tilting of the DAH during model fabrication.

FIG. 42 illustrates a waxing cap 226 used for prosthesis wax-up in orderto make a recess in the cast framework for binding the DAH 164 in place.Waxing cap has a shaft 228 and a hollow, tapered head portion 230matching the taper of processing cap 210 and a cavity 231 matching thecavity in processing cap 210 with a similar set of internal grooves 232on the inner surface of the cavity. FIGS. 43 and 44 illustrate waxingcap 226 secured over a denture attachment housing or DAH 164 secured toabutment 162 by retention member 165.

FIGS. 45 and 46 illustrate a snap-on healing cap 235 to cover up theopening of socket 168 of abutment 162 during the healing. Healing cap235 is different from prior healing caps designed to screw into theinternal threads of abutments such as abutment 102 of the firstembodiment. These internal threads are eliminated in the abutment 162 ofthis embodiment, as described above in connection with FIGS. 31 to 33.Instead of internal threads, healing cap 235 has an outer wall 236designed to engage over the outer surface 167 of abutment 162 and a stem268 extending from upper wall 270 of cap 235 which has an enlarged endportion 272 designed for frictional snap engagement with annularprojection or barb 178 in abutment socket 168 in a similar manner to thehead 196 of retention member 165, as illustrated in FIG. 47. Head or endportion 272 has a convex annular portion having spaced flats 274 aroundits outer surface, in a similar manner to the heads of retention members165B and 165C of FIGS. 35B and 35C.

FIG. 48 illustrates one embodiment of a method of attaching a dentalappliance to a plurality of implants in the lab using any of the dentalattachment assemblies described above. In a first step 300, abutmentsare secured to implants or other structures in a model. Next, the properretention members are fitted into each cap (step 302), and the caps areattached to the denture or appliance (step 304). Finally, the applianceis attached to the respective abutments using the frictionally retainedretention members (step 305). FIG. 49 illustrates an embodiment of analternative, in-mouth pick up method for securing an appliance in apatient's mouth. In this case, the abutments are secured to implants orother structure at the selected locations in the patient's mouth (step306). Selected retention members of appropriate retention forces arethen fitted into the respective caps in the appliance (step 308). Thecaps are then secured to the respective abutments via the frictionallyengaged retention members (step 310). Finally, the caps are bonded intothe appliance (step 312).

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles described herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, it is to be understood that the description anddrawings presented herein represent a presently preferred embodiment ofthe invention and are therefore representative of the subject matterwhich is broadly contemplated by the present invention. It is furtherunderstood that the scope of the present invention fully encompassesother embodiments that may become obvious to those skilled in the artand that the scope of the present invention is accordingly limited bynothing other than the appended claims.

What is claimed is:
 1. A dental attachment assembly, comprising: adenture attachment housing for securing with a dental appliance, thedenture attachment housing having an end wall and a peripheral wallextending from the end wall and having an open end defining an innercavity, the end wall having a threaded bore; an abutment configured withan outer surface, an outer opening and a socket extending inward fromthe outer opening; and a retention member having opposite first andsecond ends, a threaded portion at the first end configured for threadedengagement in the threaded bore of the end wall of the dentureattachment housing, a shaft extending from the threaded portion, and anenlarged head at the second end which is frictionally detachablyattachable with the socket of the abutment to form a frictional fitbetween the head and the socket and to retain the dental appliance andabutment with the inner cavity of the dental attachment housing engagedover the outer surface of the abutment, wherein the shaft has anenlarged annular flange, positioned at a predetermined spacing below thethreaded portion of the retention member, which engages the end wall ofthe cavity when the threaded portion is fully engaged in the threadedbore, wherein the annular flange extends perpendicular to an axialdirection of the shaft and engages an opposing surface of the innercavity of the denture attachment housing, wherein the peripheral wall ofthe denture attachment housing has a tapered outer surface which tapersoutwards in a direction towards the open end, further comprising ahealing cap configured for releasable engagement with the abutmentduring healing, the healing cap having a first end, a second open end,an outer wall extending from the first end to the second end andconfigured for engagement over the outer surface of the abutment, and astem having an enlarged end portion configured for releasable snapengagement in the socket of the abutment, and a processing cap and awaxing cap configured for attachment over the denture attachment housingduring processing of a dental appliance.
 2. The dental attachmentassembly of claim 1, wherein the threaded bore has a closed inner end.3. The dental attachment assembly of claim 1, wherein the retentionmember and abutment are securely retained at an angle of approximately20 degrees.
 4. The dental attachment assembly of claim 1, wherein theretention member is formed from a compressible material.
 5. The dentalattachment assembly of claim 4, wherein the compressible material isselected from the group consisting of polyether ether ketone (PEEK),acetal polymer material, nickel titanium (nitinol), titanium carbonitride (TiCN), and titanium.
 6. The dental attachment assembly of claim1, wherein the outer surface of the peripheral wall has at least oneanti-rotation flat.
 7. The dental attachment assembly of claim 1,wherein the processing and waxing caps each having a cavity forengagement over the outer surface of the denture attachment housing, thecavity of each cap having a tapered inner surface matching the taper ofthe outer surface of the denture attachment housing.
 8. The dentalattachment assembly of claim 1, wherein the denture attachment housingis a one part housing having an outer surface configured for bondingdirectly with a dental appliance.